A larger trip to The Czech Republic had to be postponed and my husband and I trying to salvage some of the vacation time so we are considering Ireland Sept 25 to Oct 5. We have been to Dublin before but trying to fly into one of the smaller airports adds a lot of time in airports and greatly increases airfare cost. We do not want to drive. I do have a couple of bus tours listed but generally we prefer to be more active than those tours allow.
Sept 26 land Dublin, maybe walk around Howe, have dinner, recover from 24 hours of cars, planes and airports
Sept 27 - day bus trip to Newgrange or Boyne Valley, we have never really done Celtic or Norman history in the UK or Ireland before
Sept 28 - Glendalough via St, Kevin's Bus and then transfer to Galway in the evening by bus
Sept 29, 30, Oct 1 - take ferry to Inis Mor for a day, hiking in Connemara likely via day bus tour since public buses are very limited, maybe and e-bike self-tour on the back roads of the Burren, walking around Galway. Transfer to Killarney in the evening on the 1st. I am intentionally skipping the Cliffs of Moher based on everything I have read.
Oct 2, 3, 4 - Killarney National Park walks, Gap of Dunloe hike, town sites, not sure what else. Fly? to Dublin in the evening to fly home in the morning.
Oct 5 - fly home
We could maybe add two more days but I don't know.
Do you mean Howth?
I don't know how feasible it is to get from Glendalough to Galway by bus. If you have to return to Dublin to transfer, I would take the train. You can also take the train from Killarney to Dublin.
You might consider staying in Drogheda or Malahide upon arrival for better access to the Boyne Valley. Rates will be lower than in Dublin. I like the Marcy Hotel in Drogheda. It's in the center of town, a short walk from the bus station (direct connection from airport in about an hour).
If you're able to add days, why wouldn't you?